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As editor, I confirmed that the authors have addressed all the reviewers'comments properly. Congratulations on the changes in the manuscript and making it ready for publication.
[# PeerJ Staff Note - this decision was reviewed and approved by Mike Climstein, a PeerJ Section Editor covering this Section #]
Congratulations for the changes made. While the revised manuscript resolves some issues, significant concerns remain. Please, provide a point by point answer to the reviewer. Authors must provide clear responses to address critical gaps in the study's rationale and interpretation of results.
In general, I am disappointed that the authors did not write an accompanying letter which provided answers to the issues I had raised.
The new version of the manuscript seems to have dealt with some of my issues, but not with all of them
Please answer my point 3 (mentioned in the preceding review):
3. The authors emphasize the necessity to place the tDCS electrodes on the appropriate skull location. The study is all about strength of the lower extremities and balance changes. Why did the authors choose C3 and C4 as electrode locations? Underneath C3 and C4 the hand motor cortex is located but not the leg motor cortex.
No comment
Please answer my point 5:
5. Lines 331-32: I do not understand these lines. Throughout the preceding paragraphs the authors argue that there was no difference between real and sham tDCS. Now they state that “improvements within groups were not due to spontaneous recovery but due to stimulation by tDCS“. To me, this sentence seems to contradict all that was written before.
Please clarify or modify.
The authors improved the manuscript. However, there are some major issues raised by the reviewer. These issues still need to be addressed / clarified
I thank the authors for answering a majority of the points I had raised.
However, the revised version of the manuscript still contains several aspects that should be addressed and clarified.
1. The “Stanford Accelerated Intelligent Neuromodulation Therapy“ which the authors used was not developed for tDCS but for repetitive transcranial magnetic stimulation. Moreover, it was not developed for motor functions or balance but for depression. Thus, it is unclear to me how/why the authors refer to this type of therapy.
2. Ref 33 (DaSilva et al., 2011) is mentioned directly after mentioning Stanford Accelerated Intelligent Neuromodulation Therapy but does not refer to this therapy.
3.. On page 12, the authors justify an outcome difference between their study and a study by Khedr et al by stating: “...because Khedr et al had participants who were also actively improving through natural recovery even after cessation of intervention“. Why shouldn´t this argument also be true for the authors´study? Improvements due to recovery processes occur regularly in subacute stroke populations.
4. Lines 339-341: I do not understand these lines. Throughout the preceding paragraphs the authors argue that there was no difference between real and sham tDCS. Now they state that “improvements within groups were not due to spontaneous recovery but due to stimulation by tDCS“. To me, this sentence seems to contradict all that was written before. What is meant by “majority of the times“?
5. Unfortunately, the manuscript still contains a lot of grammatical errors. It needs to be revised by a native English speaking person.
The authors emphasize the necessity to place the tDCS electrodes on the appropriate skull location. The study is all about strength of the lower extremities and balance changes. Why did the authors choose C3 and C4 as electrode locations? Underneath C3 and C4 the hand motor cortex is located but not the leg motor cortex.
No comment
The reviewers found merit in your manuscript, but major revisions were suggested. Some major issues should be clarified, according to each reviewer comment, and authors should provide a clear answer for each suggestion. For example, the rationale of the study should be clarified as well as the experimental design. Also, provide more details on sample size calculation.
This study will contribute to the ground basis of the current data and research on tCDS. Generally, the basic reporting has followed the standard format.
The objective and aim of the study are stated clearly.
However, the author should highlight more knowledge gaps in the literature and the justification, especially in the tCDS study.
In the introduction: Please highlight the theory underlying the TCDS for stroke recovery
In terms of methodology,
1. Please explain how was subacute stroke patient defined in this study.
2. When you applied tCDS, did you identify the type of stroke to be tailored to the location of the infarct in the brain area? Please mention this in your methods.
3. Since you mentioned the application for tCDS followed from new protocol. (109.110), please state the references.
4. How are you sure the conservative/conventional management was given in the standard manner, please explain in detail in your methods
In the conclusion,
1. You should also highlight that the improvement of muscle strength could be due to spontaneous recovery or conservative methods
The study has a straight-forward design. The sample size is supposed to be large enough to detect differences between both groups (if tDCS is an effective treatment). An advantage of this study is that a follow up period was included.
However, there are several issues and questions the authors should consider and answer.
General remarks:
The language needs to be checked and improved by a native English speaker.
The introduction is too long and should be more focussed. E.g., in my opinion it is unnecessary to provide a definition of “stroke“ (first paragraph of the introduction).
Line 109: please provide a reference for the “newly published protocol“.
Figure 1: Please provide an explanation for the 3 patients that were lost to follow up
Table 2: Please comment on the fact that not a single female was included. It seems to me highly improbable that only males developed strokes.
Why did the authors include informations as “nature of work“ or “pre-stroke capsulitis“ or “pre-stroke shoulder pain“? To me, they seem irrelevant for the content of this study. In my opinion the most relevant informations describing the 2 groups are age, gender, time since stroke, site of involvement, and stroke location (subcortical or cortical). The latter information is missing in this table.
Table 3 seems to me unnecessary. Only one comparison (ankle dorsi flexors at 0 weeks) was significantly different between the two groups, but due to the lack of data in this table, it is not even possible to determine which group had more strength.
Table 4: Why do the authors present the data in different sequences? The first 2 paragraphs have the sequence 0 week, 4 weeks, 8 weeks, paragraph 3 shows the sequence 4, 8, 0 weeks and paragraph 4 has the sequence 8, 0, 4 weeks.
Usually, following stroke, the strength of ankle dorsi flexors is much more reduced than the strength of ankle plantar flexors. The table suggests, however, that strength was almost the same for these two muscle groups. How do the authors explain this?
Table 7: Please provide the complete results of an ANOVA with the factors group x time and the interaction between both.
Intervention (lines 135-144): I understand that patients received 2 x 20 min of tDCS? If so, please justify why. Was the electrode placed over the M1 area of the affected hemisphere? If so, please state this clearly. Where was the other electrode placed? Which size did the electrodes have? How did the authors perform the sham stimulation? Did the physiotherapeutical treatment only last for 30 minutes per day?
Some questions regarding MMT: Was the assessor always the same person? Was the body position in which MMT was done always the same? If so, which was the position? Please comment on why the MMT was used. In my opinion grade 4 and 5 are highly assessor-dependent. Why did you not use other assessments, e.g. Timed up and Go test, Chair Stand up test, Functional Ambulation Categories, 10 m walk test?
In the discussion the authors outlined nicely that there is a vast body of evidence that tDCS has no or very small effect on strength (and also balance). Given this existing knowledge, the question arises why the authors chose these parameters?
Please perform a different type of ANOVA of the BBS data (see comment above)
All my current comments are gathered in the first 3 areas.
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